An automated data-acquisition system for the Vacuum Generators HB 501 ultrahigh-resolution dedicated scanning transmission electron microscope is being developed. The new analytical capabilities of this class of electron microscope require fresh approaches to computerization of data acquisition and analysis. Available commercial systems have been limited in both the kinds of data that can be acquired concurrently and the algorithms for processing the data. As part of this system, a desktop data-acquisition and analysis program, called DTSA, has been developed for the Macintosh II (and higher) class of computers. The data acquisition is accomplished utilizing specially modified commercial plug-in bus cards and control software routines that interface to the control and analytical software. A patent, to be held jointly by the NIH and NIST, is pending on this analytical tool.